Juventus coach Massimiliano Allegri accepts it will take time for Cristiano Ronaldo to fully settle in after his side battled to a dramatic 3-2 victory at Chievo, which shows how hard their serie a title defence will be.

Portugal forward and Ballon d’Or holder Ronaldo took centre stage at the Bentegodi on his competitive debut following a €100m summer transfer from Real Madrid.

However, it needed a huge team effort and a last-gasp winner from the defending champions to secure three points in Verona.

Following a minute’s silence in memory of the victims of Tuesday’s bridge collapse in Genoa, Sami Khedira gave Juve an early lead, which was cancelled out by a towering header from Mariusz Stepinski.

Chievo went 2-1 ahead from the penalty spot early in the second half through a penalty from former Juve winger Emanuele Giaccherini, only for an own goal by defender Mattia Bani to level things up again.

Substitute Mario Mandzukic thought he had won it with a late header, given by goal-line technology, only for the effort to be ruled out following a referral by the Video Assistant Referee after Chievo goalkeeper Stefano

Sorrentino had taken a heavy blow from Ronaldo in the build-up.

Juve, aiming to deliver a record eighth successive serie a crown, showed the spirit of champions to score a legitimate winner deep into five minutes of stoppage time when substitute Federico Bernardeschi turned in a low cross from Alex Sandro.

“It makes us realise how tough it’s going to be to win the league again,” Allegri said afterwards to the club website.

“We made a lot of mistakes today and let our focus drop. You think you’re in control and you ease off a touch, then you let your opponents get crosses in, you defend badly and you end up conceding.

“In any case, a game like that will only do us good because it makes us realise how tough it’s going to be to win the league again.”

Allegri accepts it will take time for his men to find their rhythm alongside a their new talisman.

“We’ve only had the whole squad training together for seven days,” he said.

“We’re still getting to know (Cristiano) Ronaldo. He linked up well with (Paulo) Dybala today and I was impressed by how easily he slotted into the team.

“It’s a shame he couldn’t score himself, but Sorrentino denied him a couple of times. He was happy we got the win anyway.

“(Joao) Cancelo played well in the first half, then he gave away the penalty and felt guilty about it – but you mustn’t get down over something like that.”